Malaria is a major public health problem in China. Pyrethroid-impregnated bed nets and indoor spray with pyrethroids are the main malaria vector control tools. However, the wide use of pyrethroids has resulted in the emergence and spread of resistance in mosquito populations. Insecticide resistance has significantly hindered the efforts of malaria control in China and worldwide. This application will focus on resistance mechanisms in an important malaria vector in Southern China, Anopheles minimus C. The central hypothesis is that both knockdown resistance (kdr) and metabolic detoxification confer resistance to pyrethroids in An. minimus, and consequently, the resistance level of a mosquito to pyrethroids is contingent on mutations in kdr gene and monooxygenase activity. The kdr gene polymorphism in natural populations will be determined, and correlations between the kdr mutations, monooxygenase activity with pyrethroid resistance phenotype will be examined. This research will play an important foundation for the development of molecular- or biochemically-based resistance diagnosis tools in this important malaria vector species in China and Southeast Asia. The proposed research will contribute to building research capacity in China by training one Ph.D. student and one postdoc fellow and strengthen the molecular entomology laboratory at the Nanjing Medical University. This research will be conducted as an extension of NIH grant R01 AI050243-07. PUBLIC HEALTH RELEVANCE: This application focuses on resistance mechanisms in the most important malaria vector in Southern China, Anopheles minimus C. Understanding the resistance mechanisms will play an important foundation for the development of new resistance diagnosis tools. Further, this research will contribute to building research capacity in medical entomology in China by providing research training for one Ph.D. student and one postdoc fellow, and strengthen the molecular entomology laboratory in Nanjing Medical University.